Process of impregnating wood



Aug. 24,1926. 1,597,010

K. BUBLA PROCESS OF IMPREGNATING WOOD Filed June 15, 1925 Patented Aug. 24, 1926.

UNITED STATES PATENT OFFICE.

KARL BUBLA, OF PILSEN, CZEGHOS LOVAKIA.

193001288 01 IMPREGNATING WOOD.

Application'flled Julie 15, 1926, Serial No. 87,218, andin Czechoslovakia June 20, 1924.

pressure other than normal. It is an ob qect of my invention to improve this mode of impregnation wit-l1 a view to saving time and impregnating material.

he impregnation of wood is eifected mainly with the aid of mercury chloride, copper sulphate, zinc chloride, the fluorides of differentmetals, certain phenols, nitrophenols or the salts of these compounds. As is well known to those skilled in,the art, solutions of these substances can be introduced into the wood only with difiiculty and in consequence thereof even several da s will not sufi'ice to impregnate more than the layers of wood adjoining the surface. In order to remedy this drawback it has been proposed to force the impregnating subs stance in by neumatic means. To this end the wood is introduced in a closed impregnating vat, which as a rule has the form of an iron cylinder, and part of the air 'con- ,tained in the cylinder is then removed by mode of proceeding, although'bein pumping, whereupon the impregnating solution is forced into the cylinder under a pressure of severalatmospheres, until the wood is thoroughly impregnated. 'lglhis a 1stinct im rovement of the practice ormerly followe requires a comparatively long time and involves the consumptionof considerable quantities of impregnating substances. I

I have now ascertained that the process of impre ating wood with the aid of reduced an increased pressure can'be eatly improved both as regards time an consumption of chemicals, if, after the air has been removed from the impregnating vat, instead of a. solution "having the concentration required for full im regnat ion of-the wood, a weaker'solutionlls forced into the 'wood which, owing to its lowerviscosity, readily enetrates into the interior of the wood. it the same time the cellular tissue of the wood is partly loosened, whereby the subsequent treatment with the stronger solution is greatly facilitated. Moreover, the weaker solution already'suflices for preserving the interior-"of the wood so thatit is not necessary to wait until the stron or solution which is subsequently introduce penetrates .into the interior .of the wood.

By arranging the impregnating vats in a suitable manner, for instance as described in my co-pending application for patent of the United States, filed of even date herewith, I also succeed in impregnating with the strong solution only that portion ofthe wood which is most exposed to destructive influences.

In the drawings afiixed to this specification and forming part thereof the means for practising the novel process are illustrated diagrammatically by way of example.

Referring. to the drawings, 5, 5 are the vats designed to-receive the wood to be, impregnated. In the drawing'only' a single pair of vats is shown, but I wish it to be understood that, as a rule, a batter of such vats arranged in pairs is require for the impregnation of larger masses of wood. After the vats have been filled with the wood, the covers are put on and the vats are partly evacuated by starting an air pump (not shown) connected with the pipin 22. After the reduced pressure has been alfiiwedto act during about 30 minutes the pipe 15 is opened which allows the impregnating solution to enter the lower part of the vats; This pipe is connected by means of the main 15'- with the container 33 for the dilute solution containing for instance 350 g. mercury chloride in 300 liters water. After the valves 35 have been closed, the pipings 21 leading to the compressor (not shown)- are opened. After compressed air has been allowed toact on the contentspf the vats during about 30 minutes, the pipe 15 is opened again, allowing the liquid from the vats to be forced back into the container 33, which at the same time acts v as a measuring vessel.

The main 15' is now closed and the air now sucked into the impregnating vats, I andin coming into contact withthe Wo'od thoroughly impregnates the layers of wood adjoining the surface. The action of the reduced pressure and of the dilute solution has already opened part of the cells of the wood and in consequence thereof the strong I solution can now enter with some case.

pump acting on pipe 22 is started anew.

After the vats have been filled with the concentrated solution the air pump is brought to a stand-still and pipe 21 is opened, whereby the wood is placed un der an increased pressure of about 3-7 atm., according to the density of the wood treated. Under the action of increased pressure, which is allowed to act thereon during about minutes, the wood is thoroughly impregnated. At the end of this period pipe 27 is'opened to relieve the vats of part of the pressure contained therein, the rest being utilized for expelling the liquid into the container 64 which also serves as a measuring vessel. The vats are then'opened and the wood is removed.

I wish it to be understood that I do not desire to be limited to the exact materials, proportions and sequence of operations described for. obvious modifications will occur to a person skilled in the art.

1. The method of impregnating wood comprising reducing the air pressure acting on the Wood, allowing the dilute solution of an impregnating substance to enter the wood" while thusevacuated, thereafter once more reducing the pressure acting on the wood and then allowin a stronger solution of the impregnating su stance to enter the wood. v

2. The method of impregnating wood comprising reducing the air pressure acting on the wood, forcing into the wood a dilute solution of an impregnating substance at a-pressure above the normal, removing the. dilute solution surrounding the wood,

evacuating the wood anew forcing into it a stronger solution of an impregnating substance under increased pressure and remov-' ture.

KARL BUBLA. 

